This application is a filing under 35 U.S.C. 371 of PCTJP99/02811, filed May 28, 1999.
The present invention relates to a therapeutic agent for male sterility which comprises an adenosine A1 antagonist or a salt thereof as an active ingredient and so is useful in the pharmaceutical field.
The infertile male population has recently been on the steady increase and, alongside endocrine disruptors in environment inclusive of dioxins, the so-called male sterility is a matter of serious concern to the society at large.
However, no satisfactory remedy has been established for the therapy of this disease as yet and the assisted reproductive technology such as intracytoplasmic (intraoosomal) sperm injection (ICSI) is an exclusive choice available today. ICSI is a laudably effective fertilizing method but is defective in terms of safety in that the genetic check of the sperm cannot be made. Furthermore, because the selection of fertile sperm is entrusted to the human hand, the method has ethically a negative aspect and, in addition, since the cost of the procedure is exorbitant and not covered by an insurance, many patients have to abandon the idea to receive the treatment.
Therefore, there is a keen demand from the medical scene for a fertilizing technology which would be less costly than ICSI and more natural in that the sperm would be encouraged to enter the ova by its own efforts.
The acrosomal reaction is indispensable to the penetration of sperm through the pellucid zone of the ovum and it is considered to be very efficacious to promote the induction of sperm acrosomal reaction of sperm for the therapy of male sterility.
It is generally considered that the induction of sperm acrosomal reaction in infertile men can be promoted by inhibiting the sperm phosphodiesterase and, aiming at this inhibition, such drugs as caffeine and pentoxiphylline have been used on an empirical basis.
However, the promotion of induction of sperm acrosomal reaction with such drugs has not been fruitful enough.
In the field of therapy for male sterility today, there exists a demand for an effective acrosomal reaction induction promoter and the present invention has for its object to solve the above problem.